1. Field of the invention
The invention concerns a method of manufacturing a claw-type magneto-electric rotor with claws and a rotor manufactured by a method of this kind. The invention is more particularly concerned with a method of manufacturing a magneto-electric rotor to be used in a high-speed synchronous machine and a claw-type magneto-electric rotor manufactured by this method.
2. Description of the prior art
These claw-type rotors are made up of a plurality of amagnetic and magnetic members fastened-together. The speeds employed in some high-speed synchronous machines can be 50 000 rpm or higher. As indicated hereinabove, these rotors are assemblies of component parts and for this reason manufacturers of claw-type rotors are looking to obtain rotors having the highest possible resistance to centrifugal bursting without sacrificing an optimal aerodynamic profile.
To manufacture solid rotors capable of operating at the speed mentioned above, it is necessary to use assembly techniques of the isostatic compression or similar type if the rotor is to be able to withstand bursting. During rotation, the centrifugal force that is generated is proportional to the moving mass.
Methods known in themselves of manufacturing a claw-type magneto-electric rotor of the type comprising magnetic parts forming the polarized claws of the rotor and amagnetic parts between the claws of opposite polarity, confined within an amagnetic hollow cylindrical casing, comprise a step of filling the amagnetic hollow cylinder with the magnetic and amagnetic parts and a step of isostatic compression of the assembly of the magnetic parts, the amagnetic parts and the hollow casing cylinder.
The use of isostatic compression steps means that the component parts of the rotor must be perfectly assembled. If there are any voids in which there is no material during isostatic compression, the voids are compressed, which generates displacements of the component parts that are prejudicial to the magnetic rating and to the static and dynamic mechanical equilibrium of the rotor obtained.
The least of the resulting problems would be that the rotor would not have the required optimal magnetic characteristics and the worst of these problems would be that the resulting mechanical imbalance would render the rotor unusable.
Furthermore, it is necessary for the claws to have a shape such that the machine has the highest possible efficiency.
For example, the longitudinal face of the magnetic claws facing the stator must advantageously have a progressive magnetic air gap to optimize the passage of magnetic flux between the claws and the stator of the rotating machine.
To give another example, it is necessary to dispose an amagnetic material between two adjacent magnetic masses of opposite polarity (adjacent claws). This amagnetic material limits leakage of the magnetic flux passing directly between two adjacent claws of opposite polarity, rather than passing through the stator.
The shapes of the resulting magnetic and amagnetic parts are complex, and machining them, in particular in order to obtain the tolerances imposed by the use of the isostatic compression treatment, is a long and costly process.
One aim of the present invention is to propose a method of manufacturing magneto-electric rotors of the type described hereinabove in which the machining of the complex magnetic or amagnetic parts is simplified.